Method and device for forming a tobacco strand



Dec 22, 1970 METHOD AND Filed Sept. 26. 1966 F. WILDE AL I 3,549,293

DEVICE FOR FORMING A TOBACCO STRAND 2 Sheets-Sheet 1 l NVENTORS FRIEDRICH WI LDE JOHANNES HERRMANN Dec. 22, 1970 Filed Sept. 26. 1966 F. WILDE ETAL 3,549,293

METHOD AND DEVICE FOR FORMING A TOBACCO STRAND v 2 Sheets-Sheet 2 FIG. 2

lllillllllllllllllllllll llll 26 INVENTORS FRIEDRICH WILDE JOHANNES HERRMANN United States Patent Office 3,549,293 Patented Dec. 22, 1970 3,549,293 METHOD AND DEVICE FOR FORMING A TOBACCO STRAND Friedrich Wilde and Johannes Herrmann, Dresden, Germany, assignors to VEB Tabakund Industriemaschinen Dresden, Dresden, Germany Filed Sept. 26, 1966, Ser. No. 581,842 The portion of the term of the patent subsequent to Oct. 21, 1986, has been disclaimed Int. Cl. A24c 5/18, 5/32 US. Cl. 131-21 16 Claims ABSTRACT OF THE DISCLOSURE A method and apparatus for forming a continuous strand of tobacco. Shredded tobacco is introduced into an air stream which flows along a straight line, and the stream of tobacco is compacted and reduced in cross section while it flows along the straight-line path. The stream of compacted tobacco is then directed along part of a circle which is tangent to the straight-line path, and while flowing along this part of the circle, formed by a perforated rotary suction member, for example, the speed of flow of the tobacco is reduced. While flowing at the gradually reducing speed along part of the above circle, air is drawn through the tobacco to sense the characteristics of the stream, and in accordance with this latter sensing trimming of excess tobacco takes place along the straight-line path. This trimming is derived by a counter-current air stream which removes excess tobacco.

This invention relates generally to a method and a device for forming a continuous strand of tobacco and in particular for forming a strand made from out tobacco.

Apparatus for making a tobacco strand for use in making cigarettes consists essentially of a distribution device for the cut tobacco portion wherein the portions are conveyed by an air current, an injector means, dosaging means and a strand forming system. In modern cigarette strand forming devices it is always a problem to obtain a tobacco strand of even density while simul taneously maintaining the long fiber structure and parallel positioning of the tobacco. In the known apparatus this is almost impossible because the tobacco is moved from a horizontally moving conveyor into a strand forming groove which moves beneath the conveyor. As a result, the tobacco moves rather suddenly from a horizontal to a vertical direction of movement.

Various methods and devices are known for overcoming the above mentioned problem: by means of an air current or vacuum, by centrifugal force and tangential removal of the separated fibers, by use of perforated members, and by specially formed nozzles. None of these methods has proved to be entirely satisfactory as to result, rate of production or economical operation.

It is an object of the invention to provide a method and a device for forming a strand made from fibrous tobacco, particularly from cut tobacco, wherein the tobacco portions are conveyed in an air current and wherein they are compressed to a continuous strand in the range of a strand forming device, all without sudden change of direction during the formation of the strand. Simultaneously, a relatively high strand speed is achieved and the air is separated from the tobacco strand by substantially avoiding the influence of mechanical means on the tobacco and the elimination of their disadvantageous sudden change of direction of the tobacco portions during the formation of the strand.

The advantages of the inventive device, consist in that the tobacco portions are introduced into the distribution device in a high rate of speed and are moved by a vacuum, without changing their rectilinear flow. The high rate of speed dissolves entanglements and accumulations of the tobacco fibers in the tobacco-air current, which is a prerequisite for forming an even tobacco strand.

Further advantages are clogging-free, automatic separation of the tobacco portions supplied from the distribution device and the return of the remaining tobacco portioiis into the tobacco air current. Thereby, a defined and even quantity of tobacco for the cigarette to be made is warranted.

Other advantages consist in that the uniformness and the density of the tobacco strand is influenced by applying a step-wise reduction of the air-tobacco current in the balancing chamber which has a defined cross section and a defined size. An axial pressure is produced within the balancing chamber which is effective against the cross section of the accumulated tobacco portions, being formed corresponding to the desired density of the formed strand, thus guaranteeing an even filling of the cross section of the tobacco strand. The idle air of the air current escapes in the range of the compression zone.

In order that the invention may be clearly understood, it will now be described, by way of example, with reference to the accompanying drawings, in which:

FIG. 1 is an elevational side view partially in section of an apparatus according to the invention;

FIG. 2 is a fragmentary plan view partially in section of a pneumatic tobacco transport device as used in the apparatus of FIG. 1;

FIG. 3 is a fragmentary sectional side view on an enlarged scale of a preliminary metering device as used in FIG. 1;

FIG. 4 is a fragmentary sectional view through a grooved disc of a balancing chamber as shown in side elevation in FIG. 1;

FIG. 5 is an enlarged fragmentary sectional view of a control valve; and

FIG. 6 is an enlarged fragmentary sectional view of another control valve.

With reference to the drawings and in particular to FIG. 1 thereof, it can be seen that two coacting spiked feed rollers 1 and 2 are provided which are both driven in the same direction. A beating roller 3 is arranged downstream from spiked feed rollers 1 and 2. Rollers 1, 2 and 3 are driven at a high rate of speed, the roller 2 being driven, as shown, at a somewhat greater surface speed than roller 1. These rollers feed the tobacco parts to a vacuum opening 42, constituting the inlet of a vacuum or suction pipe 4 which is arranged to discharge the tobacco parts into a tapered separator 6 comprising annular rings 5 of sheet material such as sheet metal. The separator 6 separates the tobacco particles in accordance with their mass from the air, thus operating on the basis of inertia. The separator 6 is disposed with its smallest diameter downstream of the tobacco-air current. This smallest diameter is about 1.5 to 2 times the size of the intended cross section of the tobacco strand. Vacuum pipe 4 and separator 6 are enclosed by a concentric casing 7 which extends into a feed pipe 8. The annular rings 5 act as baffles which are arranged within concentric casing 7 and extend convergingly in the direction of the flow of the tobacco-air current toward an injection nozzle 13 and the entrance orifice of the feed pipe 8. This arrangement of the bafiies facilitates the reduction of the cross-sectional area of the tobacco-air current prior to entering feed pipe 8. One or a plurality of openings 9 are provided in casing 7 which encloses vacuum pipe 4. Openings 9 are connected through the interior of the casing 7 to a powerful centrifugal exhaust fan 10 from which a further pipe 11 which is perforated in the range of a particle filter 12, converges into vacuum pipe 4. The injection nozzle 13 is axially adjustable and extends into the tobacco air current and into casing 7 at the point where separator 6 ends and where casing 7 terminates in feed pipe 8.

From the outer end of feed pipe 8 the air-tobacco current flows freely until it is received by a collecting nozzle. The collecting nozzle consists of an inner casing 14 and a surrounding counter nozzle 15. An outer casing 16'of annular counter nozzle 15, as well as inner casing 14 are separately movable in an axial direction by means of piston cylinder control arrangements 38, 39. The piston rods are connected to the casings l4 and 16 in a manner known per se by pins movable in slots and by pivotable joints. A receiving pipe 17 is provided in continuation of the collecting nozzle.

A collecting chamber 18 surrounds the feed pipe 8 to receive the counter air stream projected by the counter nozzle into the collecting chamber 18 which has one or more discharge openings 19 as well as a flow facilitating shape. The discharge opening 19 is connected through a conduit 20, depending on the position of a gate 43 in the conduit 20, either to the input end ahead of rollers 1 and 2 or to the vacuum pipe 4. A connecting line 22, which leads to the injection nozzle 13, and a further connecting line 23 to counter nozzle 15 are in communication with a source of pressure 27, such as a compressor, through shut oflf valves 25, 25 and control valves 26, 26. The lines 22 and 23 have connected thereto pressure indicators 24, 24.

The inner casing 14 of the counter nozzle 15 receives the tobacco-air stream of proper cross-sectional area at its left-hand end and leads with its right-hand end into a receiving conduit 17 which in turn leads into so-called speed adapting channel zones 33, 34 formed by a strand groove 28 in a disc or wheel 30 (FIGS. 1 and 4) and by a perforated band 29 which partially surrounds the groove 28 of disc 30 to form said channel the bottom of which is formed by a perforated base in said groove 28 in the disc 30 and the top of which is formed by said perforated band 29. The just described channel feeds the tobacco into a forming device 31. The channel zones 33, 34 adapt the higher speed of the incoming tobacco air stream to the slower speed of the forming device 31. This function will be described in more detail below.

The grooved disc 30 is described and claimed in more detail in applicants copending application 584,409 filed Oct. 5, 1966, now Pat. No. 3,473,537, issued Oct. 21, 1969.

The portion of grooved disc 30 which is not cooperating with band 29 is sealed and an adjustable separating wall 32 is provided in the used portion thereof. A pressure chamber is thus provided in this portion of grooved disc 30 and is divided into a starting zone 33, and an end zone 34. The pressure which is present in the starting zone 33 and in end zone 34 is adjustable by means of a guide plate 36. For producing a vacuum within grooved disc 30, vacuum pipe 35 is connected to the centrifugal exhaust fan 10 by means of a connecting pipe 37. However, it is also possible to connect vacuum pipe 35 to a separate vacuum source connecting pipes 37 and 37" one arranged between conduit 23 and connecting pipe 37 for receiving the spring biased pistons of control valves 26, 26' and pistons 38', 39' of piston cylinder control arrangements 38, 39. The operation of these valves will be described more fully below. The pressure fluctuations of the starting zone 33 and the end zone 34 are most effective in connecting pipe 37. Control valves 26, 26 increase or reduce the pressure in connecting pipes 22 and 23. If the density of the tobacco portions causes a relative large vacuum in disc 30, pistons 46, 46 of control valves 26,

4 26' are moved upwardly against the force of springs 40a, 40a and control valve 26 is closed relatively tighter, while control valve 26' is opened to a greater extent. Thereby, a less effective pressure is present in conduit 22, so that the speed of the air-tobacco current is also reduced in feeding pipe 8. In contrast thereto, the pressure is increased in conduit 23, so that a more effective jet stream action is produced by nozzle 14, 15, which separates a larger quantity of tobacco from the air-tobacco current. At this time the hand operated valves 25, 25' are completely open. The pneumatic control is switched off by bringing valves 26, 26' into a maximum open position by actuating their respective adjusting screws 40, 40'. Valves 25, 25' are manually closed until the desired pressure is reached and can be read from indicator devices 24, 24'.

The vacuum connecting pipe 37 is connected with the pressure chamber of grooved disc 30 and to the starting zone 33 and end zone 34 thereof. Guide plate 36, and separating wall 32 are adjustably fastened around the center of vacuum pipe 35 by means of hinges. Thereby, the guide plate 36 and the separating wall 32 may be adjusted in accordance with the prevailing pressure situation. Separating wall 32 and guide plate 36 both remain stationary during the operation of the device, once they are adjusted.

In a limited range of the upper section of vacuum pipe 35, pressure fluctuations are caused due to the continuous forming of the strand andv due to the fluctuating of the compressed portion which starts to form in the balancing chamber. Thereby, the pressure effect in connecting pipe 37 is achieved, as already described above. It should be noted that the strand has achieved a sufficient density in the end zone 34, so that the pressure remains constant in that part of the chamber.

Adjusting means 38 effects the axial displacement of counter nozzle 15 and adjusting means 39 effect the displacement of inner casing '14, in proportion to the pressure fluctuations in connecting pipe 37. The automatic control elements 26, 26', 38 and 39 may be effective individually, or selectively. The known cigarette forming device 31 is provided adjacent to the end zone 34 of the disc 30. A common variable speed gear drive 41 is provided for grooved disc 30, spiked feed rollers 1 and 2, and beating roller 3.

The device operates as follows:

The cut tobacco is conveyed into the direction of the tobacco-air current by means of the spiked feed rollers 1 and 2 and the beating roller 3 and is moved forward at a high rate of speed by an air-tobacco stream produced in vacuum pipe 4, so that the tobacco portions are effectively separated and are introduced into said separator 6. The air-tobacco stream is produced by the centrifugal exhaust fan 10 which is coupled to the separator 6 and to a suction nozzle 42 of vacuum pipe 4. The suction nozzle 42 extends over the whole width of the distribution device (see FIG. 2). The air-tobacco current in the suction pipe 4 has a relatively large cross-sectional area until it is moved into the vacuum zone of injector nozzle 13 where such cross-sectional area is reduced to 1.5 to 2 times the diameter of the intended cigarette diameter. The reduction of cross-sectional area takes place simultaneously with an increase in the speed of the air-tobacco stream or current. For this purpose, feed pipe 8 which has the desired small diameter is coupled to the discharge orifice of separator 6. Injector nozzle 13 blows or discharges the tobacco portions from the separator into feed after the exhaust air and the dust are separated in the filter 12.

An axially disposed preliminary trimming section through which the tobacco-air current flows, is arranged following the above described feeding section for the tobacco particles. The tobacco-air current which leaves feed pipe 8 enters the preliminary trimming section where it is concentrically divided by means of an adjustable counter current which axially surrounds the tobacco-air current and removes its less dense periphery to leave only its more dense core which is received by a collecting nozzle comprising the inner casing or jacket 14 and the annular counter nozzle 15, whence the denser core of the tobaccoair current is transferred to the next operating step. The just described division of the tobacco-air current corresponds to a preliminary trimming and serves the purpose to automatically reduce the irregularrtles 1n the tobacco-air current density to a desired tolerance. The cross-sectional area of the tobacco air current and of the outer ring portion may be controlled by the following factors: (1) the pressure of the counter current issuing from the counter nozzle 15, (2) the direction of the counter current relative to the tobacco air current, (3) the distance of counter nozzle 15 from feed pipe 8, as well as the (4) pressure at the injector nozzle 13. The radial size of the current and the ring size of the counter current may be controlled by adjusting any one or all four of the just mentioned factors. The degree of such ad ustments determines the amount of the tobacco-air current WhlCh is separated. For this purpose, the distribution device feeds a superfluous quantity of tobacco to feed pipe 8, which quantity corresponds to the largest irregulanty possible relative to the desired cigarette weight so that the separated portion corresponds in its volume to the volume of the irregularity. I

The irregularities in the density of the tobacco-a1r current may be ascertained by means of known electronic devices which are not part of this invention. The varying amounts of superfluous tobacco which are separated from the tobacco-air current are returned to the distribution device. For this purpose the stream of the counter nozzle 15 is used which flows together with the separated tobacco into the collection chamber 18 surrounding the preliminary measuring section and thus into pipe 20' which feeds the separated tobacco back into the distribution device 1, 2, 3, or into the vacuum pipe 4 depending upon the position of a gate 43 in pipe 20. Thus, no additional control valves are needed, because the returned tobacco is again fed to the tobacco-air current by means of spiked feed rollers 1 and 2. However, the tobacco particles are refed through the rolling elements 1, 2 and 3 as shown in FIG. 1, but this can be avoided by the gate 43. This is advantageous especially for tobacco which is brittle and sensitive to breaking.

The return of a quantity of tobacco makes it necessary to correspondingly reduce the amount of tobacco fed by the distribution device 1, 2, 3. This may be done in a known manner by measuring the tobacco-air current in feed pipe 8, or by measuring the returned tobacco in discharge opening 19 of collecting chamber 18 by means of known electronic devices, including a variable control device 21 which is actuated by results measured by a probe 21a and which in turn actuates a variable speed gear drive 41 whereby the rate of revolution of the spiked feed rollers 1 and 2 may be varied to change the quantity of tobacco fed through suction nozzle 42. An axial strand forming device receives the preliminarily trimmed tobaccoair current through receiving pipe 17 with a higher speed than that of the cigarette strand to be formed. The received tobacco-air current is not as dense as the cigarette strand. The difference in density corresponds to the difference in speed. From receiving pipe 17 the strand is moved to the speed adapting channel zones 33 and 34. The lower or end zone 34 of said channel comprises the cigarette paper for the cigarette strand. The tobacco strand is further moved to a cigarette forming conduit 44 of cigarette forming device 31. The base of strand groove 28 comprises fine sieve like holes. The groove is closed by perforated band 29 encompassing the balancing channel zones 33, 34 from the end of receiving pipe 17 to the cigarette paper. A stationary vacuum pipe 35 discharges into the inner hollow chamber of grooved disc 30. Vacuum pipe 35 is connected to centrifugal exhaust fan 10 or to an additional ventilator, not shown. Vacuum pipe 35 produces a vacuum stream in the channel zones 33, 34 due to the holes in strand groove 28. The vacuum stream is only effective in this portion of the grooved disc 30 through which the tobacco is conveyed. Therefore, the non-used portion of grooved disc 30 is sealed against the vacuum stream. The tobacco-air current which moves into the speed adapting channel zones 33, 34 at a high rate of speed is slowed down by the braking eifect of the suction produced in the channels by the vacuum in disc 30 through the holes in the bottom of the groove 28, whereby the air is removed from the tobacco air current. This operation is controlled by controlling the vacuum in disc 30 so that the tobacco assumes gradually the speed of the cigarette strand When it reaches the end zone 34, that is, before the tobacco is transferred onto the cigarette paper, the tobaccoair current assumes the speed at which the grooved disc 30 is being rotated. Hence a rather forceful vacuum effect must be produced in this range of the adapting channel. This is done by an angularly adjustable separating wall 32 within grooved disc 30. Separating wall 32 is pivotally mounted around the center of the vacuum pipe 35 and separates the vacuum chamber into two sections, that is, a starting zone 33 and an end zone 34. An adjustable guide plate 36 which also pivots around the center of vacuum pipe 35, permits the desired control of the vacuum effect in both sections. A throttle 45 in connecting pipe 37 permits controlling the total vacuum eifect.

In the end zone 34 of grooved disc 30, as already mentioned, the tobaco strand has assumed the speed of grooved disc 30 and corresponds in its compressed state to the non-shaped but otherwise finished tobacco strand. Since the vacuum effect is not as strong in the starting zone 33, the incoming tobacco-air current still has a rate of speed which is higher than the speed of grooved disc 30. Thus the tobacco particles hit the cross-sectional area of the rear end of the strand in the end zone 34, at a rather high speed which results in a 'bouncing pressure. Such pressure and the walls of the channel 34 bring about a strand compression of the tobacco particles. The still effective air of the air-tobacco current can escape through perforations in the band 29.

Grooved disc 30 and the distribution device have a common adjustable drive 41. The axial strand forming or compressing method of the tobacco strand as described heretofore results in pressure fluctuations within vacuum pipe 35 and within connecting line 37, which are used for controlling the aforementioned preliminary trimming device. If the introduced quantity of tobacco is always the same, the building up of the tobacco strand would always take place at the same level within the channel 34. However, if the delivered quantity of tobacco should become larger in the range of expected fluctuations, the strand formation level would move within the channel zones 33, 34 towards or against the direction of the tobacco air current flow. Thus a larger portion of the zones would be filled with compressed tobacco which also covers a larger portion of the strand groove 28, that is, the portion where the vacuum is applied from vacuum pipe 35. Hence, the static pressure in Vacuum pipe 35 increases corresponding to the average vacuum present therein. When the delivered quantity of tobacco does not reach the full volume, the static pressure in vacuum pipe 35 decreases. These pressure fluctuations are transmitted into longitudinal movements by pistons 38, 39' of piston-cylinder control arrangements 38, 39 which are responsive to differential pressures in line 37 and thus actuate control valves 26,

. 7 V 26'. Thereby, the four factors which influence the preliminary metering may be adjusted.

For this operation well known low inertia, pneumatic measuring and transmitting elements are used.

As described above, the tobacco portions are moved by spiked feed rollersl and 2 and by roller 3 into the vacuum orifice 42 of vacuum pipe 4. Thereby beating roller 3 shortens the tobacco particles considerably and reduces the quanity of the cigarettes. Beating roller 3 also causes undesired dust and undesired tobacco particles. It is therefore possible with the herein described invention to omit beating roller 3 by removing the tobacco particles directly from spiked feed rollers 1 and 2 and by'means of suction. nozzle or vacuum orifice 42. For this type of operation, the vacuum orifice 42 would be extended to a known tobacco retainer47 for the tobacco particles which would be arranged between spiked feed rollers 1 and 2. The subsequent strand forming method would be the same as described in the aforegoing specification.

What is claimed is:

1. In a method for forming a continuous strand of tobacco, the steps of creating an air stream which flows along a straight-line path in a given direction, directing into the air stream flowing along said path shredded tobacco to be suspended in the air stream and carried thereby along said path, initially compacting the tobacco while it flows in the air stream along said path, then deflecting the tobacco from said straight-line path along a curved path forming part of a circle which is tangent to said straight-line path, and reducing the speed of movement of the shredded tobacco as it flows along the curved path, for further compacting the tobacco.

2. In a method as recited in claim 1, directing along the outer periphery of the shredded tobacco and air stream, after it has been initially compacted and while it is still flowing along said straight-line path, a countercurrent air stream having an adjustable inner diameter and which flows oppositely to said given direction for trimming tobacco from the exterior surface of said tobacco and air stream flowing along said straight-line path to said curved path, whereby said tobacco air stream is preliminary metered.

3. In a method as recited in claim 2, directing said countercurrent trimming stream circumferentially of said tobacco air stream so as to surround the air and tobacco stream.

4. In a method as recited in claim 2, controlling the inner diameter of said countercurrent stream in response to the compacting of the tobacco flowing along the curved path, for achieving a uniform strand of tobacco at said curved path.

5. In an apparatus for continuously forming a strand of tobacco, means for creating a stream of air flowing along a straight-line path in a given direction, said means including air guides circumferentially surrounding said straight-line path and reducing the cross section of the air stream as it flows along said path, supply means for introducing shredded tobacco into said stream'to be carried thereby along said straight-line path with the shredded tobacco and being compacted where the cross section of the air stream is reduced by said air-guide means, so that the latter air-guide means also serves to compact the shredded tobacco in the stream, a rotary strand-forming suction device positioned tangentially with respect to said path for receiving the compacted tobacco and continuously forming it into a strand, said suction device including a wheel having a peripheral groove with a foraminous' bot tom and a foraminous belt closing the open radially outer portion of the groove for permitting air to be drawn therethrough, as well as suction means coacting with said wheel for retarding the movement of the shredded tobacco when it flows from the straight-line path to a curved path formed by said groove of the rotary suction wheel, so that the shredded tobacco is further compacted longitudinally of the tobacco strand as the tobacco is directed along the curved groove by the rotary suction wheel.

6. The combination of claim 5, further comprising a nozzle means situated along the stream of tobacco and air, after the initial reduction in the cross section of the tobacco and air stream with resulting compacting of the tobacco, upstream of the solution wheel for directing along the exterior surface of the shredded tobacco flowing in the tobacco and air stream a countercurrent of air flowing in a direction opposite to said given direction for trimming tobacco away from the tobacco and air stream.

7. The combination of claim 6, wherein said nozzle means circumferentially surrounds the shredded tobacco flowing along the straight-line path of the tobacco and air stream upstream of the rotary suction wheel.

8. The combination of claim 7, wherein an adjusting means coacts with said circumferential nozzle means for adjusting the latter, and detecting and control means communicating with an interior portion of the suction wheel for controlling said adjusting means to regulate the trimming action of said counter-current stream responsive to said detecting means.

9. The combination of claim 8, wherein a return means coacts with the stream of flowing shredded tobacco and air for returning the tobacco trimmed away by said counter-current air stream to the tobacco supply means.

10. The combination of claim 9, wherein said return means comprises gate means adapted to return the trimmed away tobacco directly into the air stream.

11. The combination of claim '9, wherein said rotary suction wheel has a hollow interior communicating with a source of vacuum so that air is removed by suction from the strand forming on the rotary suction wheel, and a blade situated in a plane which contains the axis of the rotary suction wheels and which is adjustable around the axis to be situated between a first arcuate portion of the wheel where shredded tobacco is initially received in a relatively loose condition and a second arcuate portion where the tobacco has already been compacted and moves at the same speed as the rotary speed of the suction wheel pressure in the hollow interior of said suction wheel, the

upstream of said blade coacting with the adjusting means for said counterflow nozzle means to adjust the latter.

12. The combination of claim 5, wherein the air guide means include means providing a chamber tapering in the direction of air flow and having an internal tapered foraminous guide means for the shredded tobacco, said air flow means providing a suction in said chamber around said foraminous guide means to draw some particles which flow by inertia through the foraminous guide out of the stream of tobacco and air while the tabacco is compacted and to return the thus removed tobacco to an upstream part of the shredded tobacco in the region where it is initially introduced into the air stream.

13. The combination of claim 6, wherein said air flow means includes an injector nozzle extending along the straightline path of flow of the air and situated at the region where the tobacco and air stream have their cross sections reduced by the air guide members for discharging air into the compacted tobacco and air stream.

14. The combination of claim 13, wherein a suction conduit communicates with the interior of said suction wheel and also communicates with said injection nozzle, and diiferential piston and valve means responding to the pressure in the suction wheel for controlling the flow of air to the injection nozzle.

15. The combination of claim 13, wherein a suction conduit means communicates with the interior of said suction wheel, and said suction conduit means also communicating with said countercurrent nozzle means for the trimming air stream, and differential piston and valve means coacting with said suction conduit for controlling the air flow to said countercurrent nozzle means according to the pressure sensed in said suction wheel.

9 10 16. The combination of claim 15, wherein a mechan- 3,089,497 5/1963 Molins et a1 13121(D) ical adjusting means is adapted to respond to pressure 3,094,127 6/1963 Gamberini 131--21(D) in said suction conduit for axially adjusting the position 3,244,184 4/1966 Petro 131-84(B) of said countercurrent nozzle means. FOREIGN PATENTS References Cited 5 251,138 4/ 1964 Australia 13121 (D) 900,182 12/1953 Germ-any 13184(B) UNITED STATES PATENTS 331,333 7/1930 Great Britain 131 s4 c 3,074,413 1/1963 McAl'thur 13184(B) 2,635,301 4/ 1953 Schubert et a1. 131-84BUX JOSEPH REICH, Primary Examiner 2,932,300 4/1960 Dearsley 13184BUX 10 3,019,793 2/1962 Labb 13184(B) U.S. Cl. X.R. 3,039,474 6/1962 Korber 131--84(B) 13184, 110

3,052,242 9/1962 Levadi 13121(D) 

